Retainer ring for securely retaining a first object to a second object

ABSTRACT

A retainer ring includes at least two holding sections and at least one engaging section. Each holding section has a radius of curvature equal to half of a diameter of a reduced section of a first object, e.g., an adaptor. The engaging section has a radius of curvature greater than that of the holding sections. The holding sections securely clamp the reduced section of the first object with the engaging section partially protruding out of the reduced section of the first object for engaging with a second object e.g., a box end of a wrench.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a reissue application of U.S. Pat. No. 6,691,593,issued Feb. 17, 2004, and filed on Mar. 8, 2002, with application Ser.No. 10/094,342, and claims priority from Taiwanese Patent ApplicationNo. 90220753 U, filed Nov. 28, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a retainer ring for securely retaininga first object, e.g., an adaptor or a bit, to a second object, e.g., abox end of a wrench or a shank of a screwdriver.

2. Description of the Related Art

FIG. 12A of the drawings illustrates a conventional retainer ring 1engaged in an annular groove 3 of an object 2, e.g., an adaptor. Aftermounting on the object 2, the retainer ring 1 could move to a positionshown in FIG. 12B under the action of gravity. This is because there isno means for securely retaining retainer ring 1 in the annular groove 3.As a result, as illustrated in FIG. 13, it would be impossible to mountthe object 2 into a receiving compartment 4 of, e.g., a box end of awrench, as the retainer ring 1 protrudes too much outward to be insertedinto the receiving compartment 4.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a retainer ring forsecurely retaining a first object to a second object.

In an embodiment of the invention, the first object is an adaptor andthe second object is a box end of a wrench. In another embodiment of theinvention, the first object is a bit and the second object is a shank ofa screwdriver.

A retainer ring in accordance with the present invention comprises atleast two holding sections and at least one engaging section. Eachholding section has a radius of curvature equal to a diameter radius ofa reduced section of a first object. The engaging section has a radiusof curvature greater than that of the holding sections. The holdingsections securely clamp the reduced section of the first object with theengaging section partially protruding out of the reduced section of thefirst object for engaging with a second object.

Other objects, advantages, and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a wrench, an adaptor, and aretainer ring in accordance with the present invention.

FIG. 1A is a plan view of the retainer ring in accordance with thepresent invention.

FIG. 2 is a bottom view of the adaptor and the retainer ring in anassembled state.

FIG. 3 is a sectional view of an end of the wrench, the adaptor, and theretainer ring in FIG. 2.

FIG. 4 is a sectional view similar to FIG. 3, illustrating use of theretainer ring with an end of a wrench having a hexagonal innerperiphery.

FIG. 5 is a sectional view similar to FIG. 3, illustrating a modifiedembodiment of the retainer ring in accordance with the presentinvention.

FIG. 6 is an exploded perspective view illustrating a wrench, anadaptor, and another embodiment of the retainer ring in accordance withthe present invention.

FIG. 7 is a bottom view of the adaptor and the retainer ring of FIG. 6in an assembled state.

FIG. 8 is a sectional view of the end of the wrench, the adaptor, andthe retainer ring in FIG. 7.

FIG. 9 is an exploded perspective view illustrating a bit, ascrewdriver, and another modified embodiment of the retainer ring inaccordance with the present invention.

FIG. 10 is a sectional view illustrating engagement between the bit, thescrewdriver, and the retainer ring in FIG. 9.

FIG. 11 is a view illustrating use of the retainer ring in a shankhaving a circular receiving compartment.

FIG. 12A is a sectional view illustrating engagement between aconventional retainer ring and an adaptor.

FIG. 12B is a sectional view illustrating anomalous engagement betweenthe retainer ring and the adaptor in FIG. 12A.

FIG. 13 is a schematic sectional view illustrating difficulty ofattaching the adaptor with the retainer ring mounted thereon to awrench.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, in accordance with the present invention, aretainer ring 10 is provided to securely retain a first object, e.g., anadaptor 20 to a second object, e.g., a box end of a wrench 30. Theadaptor 20 includes a first end 21 engaged in a receiving compartment 31of the box end of a wrench 30 and a second end 24 that acts as a driveend for engaging with and driving a socket (not shown). A spring-biasedball 25 is mounted to the drive end 24 of the adaptor 20 for releasablyengaging with the socket, which is conventional and therefore notdescribed in detail. The first end 21 of the adaptor 20 includes ahexagonal engaging portion 22 with a reduced section in which an annulargroove 23 is defined.

Referring to FIG. 1A, the retainer ring 10 is resilient and includes atleast two radially inward holding sections 11 and at least one radiallyoutward engaging section 12. Namely, the engaging section 12 is locatedin a position radially outward of the holding sections 11. In thisembodiment, the retainer ring 10 includes three holding sections 11located on two distal ends 11a of the retainer ring 10 and a section 11bof the retainer ring 10 opposite to an opening 13 of the retainer ring10 between the distal ends 11a. As illustrated in FIG. 1A, each holdingsection 11 has a radius of curvature r₁ from a center 0 equal to half ofa diameter of the annular groove 23 defined in the reduced section ofthe engaging portion 22. Further, the retainer ring 10 includes twoengaging sections 12 on both sides of the section 11b opposite to theopening 13 of the retainer ring 10. Each engaging section 12 has aradius of curvature r₂ greater than the radius of curvature r₁ of theholding sections 11. Preferably, the retainer ring 10 has a uniformthickness d. Preferably, the radius of curvature r₂ of the engagingsections 12 is greater than the radius of curvature r₁ of the holdingsections 11 by an amount t less than a thickness d of the retainer ring10.

Thus, when the retainer ring 10 is mounted in the annular groove 23 ofthe adaptor 20, the holding sections 11 of the retainer ring 10 securelyclamp a bottom wall 231 defining the annular groove 23. Thus, theretainer ring 10 is securely engaged in the annular groove 23 of theadaptor 20 without the risk of relative movement therebetween. This isowing to the fact that each holding section 11 has a radius of curvaturer₁ equal to half of a diameter of the reduced section of the engagingportion 22. Each engaging section 12 of the retainer ring 10 protrudesbeyond the annular groove 23 of the adaptor 20 (see the solid blacklines R and the dashed lines between the solid black lines R).

Referring to FIG. 3, when the adaptor 20 coupled with the retainer ring10 is mounted in a dodecagonal receiving compartment 31 of a wrench 30,the retainer ring 10, when compressed, would not move or wobble in theannular groove 23 of the adaptor 20, as the three holding sections 11 ofthe retainer ring 10 securely clamp the bottom wall 231 defining theannular groove 23 of the adaptor 20. Further, the engaging sections 12engage with the dodecagonal inner periphery of the receiving compartment31 at six points P. Thus, the adaptor 20 is securely engaged in thereceiving compartment 31 of the wrench 30.

When the adaptor 20 coupled with the retainer ring 10 is mounted in apolygonal receiving compartment 31 of a wrench 30, as illustrated inFIG. 4, the retainer ring 10, when compressed, would not move or wobblein the annular groove 23 of the adaptor 20, as the three holdingsections 11 of the retainer ring 10 securely clamp the bottom wall 231defining the annular groove 23 of the adaptor 20. Further, the engagingsections 12 engage with the hexagonal inner periphery of the receivingcompartment 31 at four points P. Thus, the adaptor 20 is securelyengaged in the receiving compartment 31 of the wrench 30.

FIG. 5 illustrates a modified embodiment of the retainer ring 10,wherein like numerals denotesdenote like elements. In this embodiment,the engaging portion (now designated by 22′) of the adaptor 20 iscircular, and wrench 30 has a circular receiving compartment 33. Whenmounting the adaptor 20 coupled with the retainer ring 10 is mounted inthe circular receiving compartment 33 of the wrench 30, as illustratedin FIG. 5, the retainer ring 10, when compressed, would not move orwobble in the annular groove 23 of the adaptor 20, as the three holdingsections 11 of the retainer ring 10 securely clamp the bottom wall 231defining the annular groove 23 of the adaptor 20. Further, the wholeengaging sections 12 engage with the circular inner periphery of thereceiving compartment 33 (see the solid black lines R in FIG. 5). Thus,the adaptor 20 is securely engaged in the receiving compartment 33 ofthe wrench 30.

FIG. 6 illustrates another modified embodiment of the present invention,wherein like numerals denotesdenote like elements. In this embodiment,the retainer ring 10′ includes a radially outward engaging section 12′opposite to an opening 13′ of the retainer ring 10′ and two radiallyinward holding sections 11′. Each radially inward holding section 11′includes an associated one of the distal ends (not labeled) of theretainer ring 10′. The radii of the holding section 11′ and the engagingsection 12′ in this embodiment are respectively the same as that of theholding section 11 and the engaging section 12 of the embodiment shownin FIG. 1A.

As illustrated in FIG. 7, when mounting the retainer ring 10′ to theadaptor 20, the holding sections 11′ of the retainer ring 10′ securelyclamp the bottom wall 231 defining the annular groove 23 of the adaptor20 without the risk of relative movement therebetween. Further, theengaging section 12′ of the retainer ring 10′ protrudes beyond theannular groove 23 of the adaptor 20.

When mounting the adaptor 20 coupled with the retainer ring 10′ ismounted in a dodecagonal receiving compartment 31 of a wrench 30, asillustrated in FIG. 8, the retainer ring 10′, when compressed, would notmove or wobble in the annular groove 23 of the adaptor 20, as theholding sections 11′ of the retainer ring 10 securely clamp the bottomwall 231 defining the annular groove 23 of the adaptor 20. Further, theengaging section 12′ engages with the dodecagonal inner periphery of thereceiving compartment 31 at four points P. Thus, the adaptor 20 issecurely engaged in the receiving compartment 31 of the wrench 30.

FIG. 9 illustrates a further modified embodiment of the presentinvention. In this embodiment, the retainer ring 10′ includes a radiallyoutward engaging section 12′ opposite to an opening 13′ of the retainerring 10′ and two radially inward holding sections 11′. Each radiallyinward holding section 11′ includes an associated one of the distal ends(not labeled) of the retainer ring 10′. The retainer ring 10′ securelyretains a bit 20′ to a shank 30′ of a screwdriver. An end 22′ of the bit20′ is hexagonal and includes a reduced section having an annular groove23′ defined by a bottom wall 231′. A drive end 24′ is formed on theother end of the bit 20′. The shank 30′ of the screwdriver includes areceiving compartment 32′. The radii of the holding section 11′ and theengaging section 12′ in this embodiment are respectively the same asthat of the holding section 11 and the engaging section 12 of theembodiment shown in FIG. 1A.

As illustrated in FIG. 10, when mounting the retainer ring 10′ to thebit 20′, the holding sections 11′ of the retainer ring 10′ securelyclamp the bottom wall 231′ defining the annular groove 23′ of the bit20′ without the risk of relative movement therebetween. Further, theengaging section 12′ of the retainer ring 10′ protrudes beyond theannular groove 23′ of the bit 20′.

When the bit 20′ coupled with the retainer ring 10′ is mounted in thehexagonal receiving compartment 32′ of the shank 30′, as illustrated inFIG. 10, the retainer ring 10′, when compressed, would not move orwobble in the annular groove 23′ of the bit 20′, as the holding sections11′ of the retainer ring 10′ securely clamp the bottom wall 231′defining the annul groove 23′ of the bit 20′. Further, the engagingsection 12′ engages with the hexagonal inner periphery of the receivingcompartment 32′ at three points P. Thus, the bit 20′ is securely engagedin the receiving compartment 32′ of the shank 30′.

FIG. 11 illustrates still another modified embodiment that is modifiedfrom the embodiment of FIGS. 9 and 10. In this embodiment, the end 22′of the bit 20′ is circular and the receiving compartment (now designatedby 33′) of the shank 30′ is also circular. When the bit 20′ coupled withthe retainer ring 10′ is mounted in the circular receiving compartment33′ of the shank 30′, as illustrated in FIG. 10, the retainer ring 10′would not move or wobble in tothe annular groove 23′ of the bit 20′ whencompressed, as the holding sections 11′ of the retainer ring 10′securely clamp the bottom wall 231′ defining the annular groove 23′ ofthe bit 20′. Further, the engaging section 12′ engages with the circularinner periphery of the receiving compartment 33′ (see the solid blackline R). Thus, the bit 20′ is securely engaged in the receivingcompartment 33′ of the shank 30′. The radii of the holding section 11′and the engaging section 12′ in this embodiment are respectively thesame as that of the holding section 11 and the engaging section 12 ofthe embodiment shown in FIG. 1A.

It is noted that the numbers number and the shapes of the holdingsections 11, 11′ and the engaging sections 12, 12′ may vary according tothe need.

Although the invention has been explained in relation to its preferredembodiment, it is to be understood that many other possiblemodifications and variations can be made without departing from thescope of the invention as hereinafter claimed.

1. A retainer ring designed for securely radially retaining anengagement portion of a first object, having a reduced portion of aradially reduced cross-section, to in a receiving compartment of asecond object, the retainer ring having a substantially uniform radialthickness along the circumference of the retainer ring and beingresilient and comprising: a plurality of circumferential sections ofsaid uniform thickness, the circumferential sections including at leasttwo holding sections and at least one engaging section, said at leastone engaging section defining an outward portion having an outer radiusof curvature which is greater than an outer radius of curvature of theholding sections, each of said at least two holding sections having aninner radius of curvature equal to half of a diameter of the reducedcross-section of the reduced portion of the first object, said at leastone engaging section having an inner radius of curvature which isgreater than that of said at least two holding sections, and thecurvatures of the holding sections and of the engaging section eachhaving a center of curvature within the circumference of the retainerring; wherein said at least two holding sections being adapted toprovidefor securely radially inward clampclamping of said reduced cross-sectionof said first object withand the retainer ring is radially compressibleand designed to be radially compressed for radially inward clamping ofthe holding sections on the reduced cross-section of the reduced portionof the first object when said outward portion of said at least oneengaging section partially protruding out of said reduced section ofsaid first object for engaging with said second objectis pressed in aradially inward direction.
 2. The retainer ring as claimed in claim 1,wherein said retainer ring includes two distal ends spaced by anopening, each of said distal ends of said retainer ring forming anassociated one of said at least two holding sections.
 3. The retainerring as claimed in claim 2, wherein a third holding section of said atleast two holding sections of said retainer ring is located in aposition opposite to said opening.
 4. The retainer ring as claimed inclaim 1, wherein said retainer ring includes an a circumferentialopening and wherein said at least one engaging section of said retainerring is opposite to said opening.
 5. The retainer ring as claimed inclaim 1, wherein said inner radius of curvature of said at least oneengaging section is greater than said inner radius of curvature of saidat least two holding sections by an amount less than said thickness ofsaid retainer ring.
 6. The retainer ring as claimed in claim 2, whereinsaid inner radius of curvature of said at least one engaging section isgreater than said inner radius of curvature of said at least two holdingsections by an amount less than a said thickness of said retainer ring.7. The retainer ring as claimed in claim 3, wherein said inner radius ofcurvature of said at least one engaging section is greater than saidinner radius of curvature of said at least two holding sections by anamount less than a a said thickness of said retainer ring.
 8. Theretainer ring as claimed in claim 4, wherein said inner radius ofcurvature of said at least one engaging section is greater than saidinner radius of curvature of said at least two holding sections by anamount less than a a said thickness of said retainer ring.
 9. Acombination comprising: a first object that including includes anengagement portion and a reduced portion of a radially reducedcross-section formed in the engagement portion; a second object thatincluding includes a receiving compartment; and a resilient retainerring designed for radially retaining the engagement portion of the firstobject in the receiving compartment of the second object, the retainerring having a substantially uniform radial thickness along thecircumference thereof and comprising a plurality of circumferentialsections of said uniform thickness, the circumferential sectionsincluding at least two holding sections and at least one engagingsection, said at least one engaging section defining an outward portionhaving an outer radius of curvature that is greater than an outer radiusof curvature of the holding sections, each of said at least two holdingsections having an inner radius of curvature equal to half of a diameterof said reduced cross-section of said reduced portion of the engagementportion of the first object, said at least one engaging section havingan inner radius of curvature greater than that of said at least twoholding sections, the curvatures of the holding sections and of theengaging section each having a center of curvature within thecircumference of the retainer ring, said at least two holding sectionssecurely clamping said reduced section of said first object withwhereinthe retainer ring, when mounted on the reduced cross-section of theengagement portion of the first object and when the engagement portionof the first object is received in the receiving compartment of thesecond object, has said outward portion of said at least one engagingsection partially protruding out of said reduced sectionportion of saidfirst object forengagement portion beyond an outer periphery thereof andsaid outward portion is radially engagingengaged with an inner peripheryof said receiving compartment of said second object, with engagement ofthe at least one engaging section with the second object providing forclamping of the at least two holding sections, so that the retainer ringis radially compressed and the at least two holding sections aresecurely clamped about the reduced cross-section of the reduced portionof the engagement portion.
 10. The combination as claimed in claim 9,wherein said retainer ring includes two distal ends spaced by anopening, each of said distal ends of said retainer ring forming anassociated one of said at least two holding sections.
 11. Thecombination as claimed in claim 10, wherein a third holding section ofsaid at least two holding sections is opposite to said opening.
 12. Thecombination as claimed in claim 9, wherein said retainer ring includesan a circumferential opening and wherein said at least one engagingsection of said retainer ring is opposite to said opening.
 13. Thecombination as claimed in claim 9, wherein the first object is anadaptor and the second object is a box end of a wrench.
 14. Thecombination as claimed in claim 9, wherein the first object is a bit andthe second object is a shank of a screwdriver.
 15. The combination asclaimed in claim 9, wherein said inner radius of curvature of said atleast one engaging section is greater than said inner radius ofcurvature of said at least two holding sections by an amount less than aa said thickness of said retainer ring.
 16. The combination as claimedin claim 10, wherein said inner radius of curvature of said at least oneengaging section is greater than said inner radius of curvature of saidat least two holding sections by an amount less than a said thickness ofsaid retainer ring.
 17. The combination as claimed in claim 11, whereinsaid inner radius of curvature of said at least one engaging section isgreater than said inner radius of curvature of said at least two holdingsections by an amount less than a said thickness of said retainer ring.18. The combination as claimed in claim 12, wherein said inner radius ofcurvature of said at least one engaging section is greater than saidinner radius of curvature of said at least two holding sections by anamount less than a said thickness of said retainer ring.
 19. Thecombination as claimed in claim 13, wherein said inner radius ofcurvature of said at least one engaging section is greater than saidinner radius of curvature of said at least two holding sections by anamount less than a said thickness of said retainer ring.
 20. Thecombination as claimed in claim 14, wherein said inner radius ofcurvature of said at least one engaging section is greater than saidinner radius of curvature of said at least two holding sections by anamount less than a said thickness of said retainer ring.
 21. Theretainer ring as claimed in claim 3, wherein said at least one engagingsection comprises a first engaging section and a second engagingsection, the first engaging section between the third holding sectionand one of said distal ends of the retainer ring and the second engagingsection between the third holding section and the other of said distalends.
 22. The retainer ring as claimed in claim 21, wherein the innerradius of curvature of said at least one engaging section is constantalong a circumferential length of the engaging section.
 23. The retainerring as claimed in claim 4, wherein the retainer ring includes twodistal ends spaced by said opening, and one of said at least two holdingsections extends between said at least one engaging section and one ofsaid distal ends, and the other of said at least two holding sectionsextends between said at least one engaging section and the other of saiddistal ends.
 24. The retainer ring as claimed in claim 23, wherein theinner radius of curvature of said at least one engaging section isconstant along a circumferential length of the engaging section.
 25. Theretainer ring as claimed in claim 11, wherein said at least one engagingsection comprises a first engaging section and a second engagingsection, the first engaging section extending between the third holdingsection and one of said distal ends of the retainer ring and the secondengaging section extending between the third holding section and theother of said distal ends.
 26. The retainer ring as claimed in claim 25,wherein the inner radius of curvature of said at least one engagingsection is constant along a circumferential length of the engagingsection.
 27. The retainer ring as claimed in claim 12, wherein theretainer ring includes two distal ends spaced by said opening, and oneof said at least two holding sections extends between said at least oneengaging section and one of said distal ends, and the other of said atleast two holding sections extends between said at least one engagingsection and the other of said distal ends.
 28. The retainer ring asclaimed in claim 27, wherein the inner radius of curvature of said atleast one engaging section is constant along a circumferential length ofthe engaging section.
 29. The retainer ring as claimed in claim 28,wherein the first and second holding sections have an inner radius ofcurvature equal to half of a diameter of the reduced cross-section ofthe first object along a circumferential length of the holding sections.30. A retainer ring for radially retaining an engagement portion of afirst object, including a reduced portion of a radially reducedcross-section, in a receiving compartment of a second object, theretainer ring having a substantially uniform radial thickness along thecircumference of the retainer ring and being resilient and comprising: aplurality of circumferential sections of said uniform thickness, thecircumferential sections including first and second holding sections anda first engaging section, the first engaging section having an innerradius of curvature that is greater than an inner radius of curvature ofthe first and second holding sections, and the first engaging sectiondefining outward portions having an outer radius of curvature which isgreater than an outer radius of curvature of said first and secondholding sections, the curvatures of the first engaging section and ofthe outward portions thereof each having a center of curvature withinthe circumference of the retainer ring, said retainer ring furtherincluding first and second distal ends spaced by an opening; whereinsaid first and second holding sections provide for securely radiallyinward clamping of said reduced cross-section of the reduced portion ofsaid first object, and the retainer ring is radially compressible anddesigned to be radially compressed for radially inward clamping of thefirst and second holding sections on the reduced cross-section of thereduced portion of the first object when said outward portions of thefirst engaging section are pressed in a radially inward direction. 31.The retainer ring as claimed in claim 30, the first and second distalends of said retainer ring forming respectively the first and secondholding sections.
 32. The retainer ring as claimed in claim 31, furthercomprising a third holding section located in a position opposite tosaid opening.
 33. The retainer ring as claimed in claim 32, wherein saidfirst engaging section protrudes radially outward from said at least oneof said first and second holding sections by a distance less than saidthickness of said retainer ring.
 34. The retainer ring as claimed inclaim 31, wherein said first engaging section protrudes radially outwardfrom said at least one of said first and second holding sections by adistance less than said thickness of said retainer ring.
 35. Theretainer ring as claimed in claim 30, wherein said first engagingsection of said retainer ring is opposite to said opening.
 36. Theretainer ring as claimed in claim 35, wherein said first engagingsection protrudes radially outward from said at least one of said firstand second holding sections by a distance less than said thickness ofsaid retainer ring.
 37. The retainer ring as claimed in claim 30,wherein said first engaging section protrudes radially outward from saidat least one of said first and second holding sections by a distanceless than said thickness of said retainer ring.
 38. The retainer ring asclaimed in claim 30, wherein the first object is a bit and the secondobject is a shank of a screwdriver.
 39. The retainer ring as claimed inclaim 30, wherein the first object is an adaptor and the second objectis a box end of a wrench.
 40. The retainer ring as claimed in claim 30,further comprising a third holding section and a second engagingsection, the first engaging section between the third holding sectionand one of said distal ends of the retainer ring and the second engagingsection between the third holding section and the other of said distalends.
 41. The retainer ring as claimed in claim 40, wherein the innerradius of curvature of the first engaging section is constant along acircumferential length of the engagement section.
 42. The retainer ringas claimed in claim 30, wherein the first holding section extendsbetween said first engaging section and one of said distal ends, and thesecond holding sections extends between said first engaging section andthe other of said distal ends.
 43. The retainer ring as claimed in claim42, wherein the inner radius of curvature of the first engaging sectionis constant along a circumferential length of the engagement section.44. A combination comprising: a first object that includes an engagementportion and a reduced portion of a radially reduced cross-section formedinto the engagement portion; a second object that includes a receivingcompartment; and a resilient retainer ring designed for radiallyretaining the engagement portion of the first object in the receivingcompartment of the second object, the retainer ring having asubstantially uniform radial thickness along the circumference thereofand comprising a plurality of circumferential sections of said uniformthickness, the circumferential sections including first and secondholding sections and a first engaging section, the first engagingsection having an inner radius of curvature which is greater than aninner radius of curvature of the first and second holding sections, andthe first engaging section defining outward portions having an outerradius of curvature which is greater than an outer radius of curvatureof the first and second holding sections, the curvatures of the firstengaging section each having a center of curvature within thecircumference of the retainer ring; said retainer ring including firstand second distal ends spaced by an opening, said first and seconddistal ends of said retainer ring forming respectively said firstholding section and said second holding section; wherein the retainerring, when mounted on the reduced portion of the engagement portion ofthe first object, and when the engagement portion of the first object isreceived in the receiving compartment of the second object, has theoutward portions of said first engaging section protruding out of saidreduced portion of said engagement portion beyond an outer peripherythereof and the outward portions are radially engaged by an innerperiphery of said receiving compartment of said second object, so thatthe retainer ring is radially compressed and the first and secondholding sections are radially inwardly clamped about the reducedcross-section of said reduced portion.
 45. The combination as claimed inclaim 44, further comprising a third holding section opposite to saidopening.
 46. The combination as claimed in claim 45, wherein said firstengaging section protrudes radially outward from said at least one ofsaid first and second holding sections by a distance less than saidthickness of said retainer ring.
 47. The combination as claimed in claim44, wherein said first engaging section of said retainer ring isopposite to said opening.
 48. The combination as claimed in claim 47,wherein said first engaging section protrudes radially outward from saidat least one of said first and second holding sections by a distanceless than said thickness of said retainer ring.
 49. The combination asclaimed in claim 44, wherein the first object is an adaptor and thesecond object is a box end of a wrench.
 50. The combination as claimedin claim 49, wherein said first engaging section protrudes radiallyoutward from said at least one of said first and second holding sectionsby a distance less than said thickness of said retainer ring.
 51. Thecombination as claimed in claim 44, wherein the first object is a bitand the second object is a shank of a screwdriver.
 52. The combinationas claimed in claim 51, wherein said first engaging section protrudesradially outward from said at least one of said first and second holdingsections by a distance less than said thickness of said retainer ring.53. The combination as claimed in claim 44, wherein said first engagingsection protrudes radially outward from said at least one of said firstand second holding sections by a distance less than said thickness ofsaid retainer ring.
 54. The combination as claimed in claim 49, whereinthe adaptor comprises a polygonal engaging portion including an annulargroove.
 55. The combination as claimed in claim 54, wherein the adaptorcomprises a drive end adapted for driving a socket.
 56. The combinationas claimed in claim 55, wherein the box end of the wrench comprises apolygonal receiving compartment.
 57. The combination as claimed in claim55, wherein the box end of the wrench comprises a dodecagonal innerperiphery.
 58. The combination as claimed in claim 49, wherein the boxend of the wrench comprises a polygonal receiving compartment.
 59. Thecombination as claimed in claim 49, wherein the box end of the wrenchcomprises a dodecagonal inner periphery.
 60. The retainer ring asclaimed in claim 44, further comprising a third holding section and asecond engaging section, the first engaging section between the thirdholding section and one of said distal ends of the retainer ring and thesecond engaging section between the third holding section and the otherof said distal ends.
 61. The retainer ring as claimed in claim 60,wherein the inner radius of curvature of the first engaging section isconstant along a circumferential length of the engagement section. 62.The retainer ring as claimed in claim 44, wherein the first holdingsection extends between said first engaging section and one of saiddistal ends, and the second holding sections extends between said firstengaging section and the other of said distal ends.
 63. The retainerring as claimed in claim 62, wherein the inner radius of curvature ofthe first engaging section is constant along a circumferential length ofthe engagement section.
 64. The retainer ring as claimed in claim 62,wherein the first and second holding sections have an inner radius ofcurvature equal to half of a diameter of the reduced cross-section ofthe first object along a circumferential length of the holding sections.65. A combination comprising: an adaptor that includes an engagementportion and a reduced portion of a radially reduced cross-section formedinto the engagement portion; a box end of a wrench that includes areceiving compartment; and a resilient retainer ring designed forradially retaining the engagement portion of the adaptor in thereceiving compartment of the box end of the wrench, the retainer ringhaving a substantially uniform radial thickness along the circumferencethereof and comprising a plurality of circumferential sections of saiduniform thickness, the circumferential sections including first, second,and third holding sections and further including first and secondengaging sections, the first engaging section having an inner radius ofcurvature greater than an inner radius of curvature of each of theholding sections and defining a first outward portion having an outerradius of curvature that is greater than an outer radius of curvature ofeach of the holding sections, the curvatures of the first engagingsection and of said first outward portion each having a center ofcurvature within the circumference of the retainer ring, the secondengaging section defining a second outward portion having an outerradius of curvature which is greater than an outer radius of curvatureof each of the holding sections; said retainer ring further includingfirst and second distal ends spaced by an opening, said third holdingsection being opposite to said opening, the first engaging sectionextending between the first holding section and the third holdingsection, and the second engaging section extending between the secondholding section and the third holding section; wherein the retainerring, when mounted on the reduced portion of the engagement portion ofthe adaptor, has said first, second and third holding sections securelyclamping radially on said reduced portion of said engagement portion andhas said outward portions of said first and second engaging sectionsprotruding out of said reduced portion of said engagement portion beyondan outer periphery thereof, and said outward portions radially engagewith an inner periphery of said receiving compartment of said box end,when the engagement portion is received in the receiving compartment ofsaid box end of a wrench, so that the retainer ring is radiallycompressed and the first, second and third holding sections are radiallyinwardly clamped about the reduced portion of the engagement portion.66. The combination as claimed in claim 65, wherein the adaptorcomprises a polygonal engaging portion including an annular groove. 67.The combination as claimed in claim 66, wherein the adaptor comprises adrive end adapted for driving a socket.
 68. The combination as claimedin claim 66, wherein the box end of the wrench comprises a receivingcompartment having a hexagonal inner periphery, and wherein the outwardportions of the first and second engaging sections of the retainer ringengage with the hexagonal inner periphery of the receiving compartmentat four points.
 69. The combination as claimed in claim 68, wherein saidfirst engaging section protrudes radially outward from said first andsecond holding sections by a distance less than said thickness of saidretainer ring.
 70. The combination as claimed in claim 69, wherein saidsecond engaging section protrudes radially outward from said second andthird holding sections by a distance less than said thickness of saidretainer ring.
 71. The combination as claimed in claim 68, wherein saidsecond engaging section protrudes radially outward from said second andthird holding sections by a distance less than said thickness of saidretainer ring.
 72. The combination as claimed in claim 66, wherein thebox end of the wrench comprises a dodecagonal inner periphery andwherein the outward portions of the first and second engaging sectionsof the retainer ring engage with the dodecagonal inner periphery at sixpoints.
 73. The combination as claimed in claim 72, wherein said firstengaging section protrudes radially outward from said first and secondholding sections by a distance less than said thickness of said retainerring.
 74. The combination as claimed in claim 73, wherein said secondengaging section protrudes radially outward from said second and thirdholding sections by a distance less than said thickness of said retainerring.
 75. The combination as claimed in claim 72, wherein said secondengaging section protrudes radially outward from said second and thirdholding sections by a distance less than said thickness of said retainerring.
 76. The combination as claimed in claim 65, wherein said firstengaging section protrudes radially outward from said first and secondholding sections by a distance less than said thickness of said retainerring.
 77. The combination as claimed in claim 76, wherein said secondengaging section protrudes radially outward from said second and thirdholding sections by a distance less than said thickness of said retainerring.
 78. The combination as claimed in claim 66, wherein said secondengaging section protrudes radially outward from said second and thirdholding sections by a distance less than said thickness of said retainerring.
 79. A combination of a first object and a radially resilientretainer ring, the retainer ring mounted on a reduced portion of anengagement portion and designed for radially retaining the engagementportion in a receiving compartment of a second object, the first objectincluding the engagement portion and the reduced portion of theengagement portion is formed into the engagement portion to have aradially reduced cross-section, the retainer ring including two distalends spaced by an opening and having a substantially uniform radialthickness along the circumferential length thereof, the retainer ringfurther including a plurality of circumferential sections of saiduniform thickness, the circumferential sections including first andsecond holding sections and a first engaging section, the first andsecond holding sections having an inner radius of curvature that isequal to half of a diameter of the cross-section of the reduced portionof said engagement portion, and the first engaging section having aninner radius of curvature that is greater than said inner radius ofcurvature of the holding sections, the first engaging section definingan outward portion that protrudes outwardly beyond a periphery of theengagement portion and has an outer radius of curvature that is greaterthan an outer radius of curvature of the holding sections, each of saidcurvatures having a center of curvature inside the periphery of theretainer ring, wherein the reduced portion of said engagement portion isradially clamped by the holding sections and the retainer ring isradially compressible and is designed to be compressed for radiallyinward clamping of the holding sections onto the reduced section whenthe outward portion of the engaging section is pressed in a radiallyinward direction of the retainer ring.
 80. The combination as claimed inclaim 79, wherein the first holding section includes one of said distalends of the retainer ring, and the second holding section includes theother of the distal ends of the retainer ring.
 81. The combination asclaimed in claim 79, wherein the circumferential sections of theretainer ring further include a second engaging section defining anoutward portion protruding outwardly beyond the periphery of theengagement portion of the first object and having an outer radius ofcurvature that is greater than an outer radius of curvature of each ofthe holding sections, wherein the curvature has a center of curvaturewithin the periphery of the retainer ring.
 82. The combination asclaimed in claim 81, wherein the inner radius of curvature of the firstengaging section and an inner radius of curvature of the second engagingsection each is greater than the inner radius of curvature of the firstand second holding sections by an amount less than said thickness of theretainer ring.
 83. The combination as claimed in claim 79, wherein aninner radius of curvature along circumferential lengths of the holdingsections is defined by said inner radius of curvature of the first andsecond holding sections.
 84. The combination as claimed in claim 79,wherein the inner radius of curvature of the first engaging section isgreater than the inner radius of curvature of the first and secondholding sections by an amount less than said thickness of the retainerring.
 85. The combination as claimed in claim 79, wherein the peripheryof the engagement portion of the first object is hexagonal, and anoutward portion is defined by each of two circumferential ends of saidfirst engaging section and protrudes outwardly beyond the periphery ofthe engagement portion and has an outer radius of curvature greater thanan outer radius of curvature of the holding sections.
 86. Thecombination as claimed in claim 79, wherein the first engaging sectionis opposite to said opening, and the first holding section extendsbetween the first engaging section and one of said distal ends of theretainer ring, and the second holding section extends between the firstengaging section and the other of said distal ends of the retainer ring.87. The combination as claimed in claim 86, wherein the inner radius ofcurvature of the first engaging section is constant along acircumferential length of the engaging section.
 88. The combination asclaimed in claim 87, wherein the inner radius of curvature of the firstengaging section is greater than the inner radius of curvature of thefirst and second holding sections by an amount less than said thicknessof the retainer ring.
 89. The combination as claimed in claim 86,wherein the periphery of the engagement portion of the first object ishexagonal, and an outward portion is defined by each of twocircumferential ends of said first engaging section and protrudesoutwardly beyond the periphery of the engagement portion and has anouter radius of curvature greater than an outer radius of curvature ofthe holding sections.
 90. The combination as claimed in claim 79,wherein the circumferential sections of the retainer ring furtherinclude a third holding section and a second engaging section, the thirdholding section being opposite to said opening, the first engagingsection extending between the first holding section and the thirdholding section, and the second engaging section extending between thesecond holding section and the third holding section.
 91. Thecombination as claimed in claim 90, wherein the first and secondengaging sections each have an inner radius of curvature that isconstant along a circumferential length of the engaging section.
 92. Thecombination as claimed in claim 90, wherein the third holding sectionhas an inner radius of curvature that is equal to half of a diameter ofthe reduced portion of the engagement portion of the first object. 93.The combination as claimed in claim 90, wherein the inner radius ofcurvature of the first and second engaging section is greater than aninner radius of curvature of the third holding section by an amount lessthan said thickness of the retainer ring.
 94. The combination as claimedin claim 90, wherein the periphery of the engagement portion of thefirst object is hexagonal and an outward portion protruding outwardlybeyond the periphery of the engagement portion and having an outerradius of curvature greater than an outer radius of curvature of each ofthe holding sections is defined by each of two circumferential ends ofeach of the first and second engaging sections.